Room surface finishes can play a significant role in maximizing the efficiency of a lighting system because lighter finishes can produce relatively higher light levels and perceptions of brightness. In fact, in an existing space with a large area of dark surfaces can improve light levels and visual comfort almost immediately by simply repainting those surfaces a lighter color to improve reflectance—and thereby improve coefficient of utilization, an expression of efficiency of a luminaire in a given application and an important factor in design light level calculations.
| Office | K-12 School | Small Retail | Small Hospital and Healthcare | Warehouse and Self-Storage |
| Ceiling: >80% (90% if indirect lighting) Walls: >70% (same for >2.5-ft. vertical partitions) | Ceiling: 70% (preferred 80-90%) Walls: 50% Floor: 20% | Ceiling: 80% (80+% if daylight zone) Wall: 50% (70+% if daylight zone) Floor: 20% | Ceiling: 85% (direct lighting) and at least 90% (indirect and/or daylighting) Walls: 50% (70% for walls adjacent to daylight apertures) Floor: 20% | Ceiling: 80% Walls: 30% Product/Floor: 20% |
Update: The right side of the table is getting cut off, so here’s the text for Warehouse/Self-Storage … Ceiling: 80%, Walls: 30%, Product/Floor: 20%.
Source: ASHRAE/IES Advanced Energy Design Guides.
